HIV vaccine 'could be on the market in five years'

A vaccine against Aids could be available within five years if it is shown to prevent HIV infection in at least a third of the people taking part in two clinical trials due to end next year, an American biotechnology company said yesterday.

Vaxgen, which is based in California, is the only company testing a potential Aids vaccine in phase-three clinical trials – the final stage before drugs are approved for wider use – and will analyse the results in 2003 to see if the vaccine actually prevents HIV infection.

Yesterday, at the international Aids conference in Barcelona, Vaxgen said early indications showed that most of the nearly 8,000 volunteers in the two trials taking place in the US and Thailand are producing the necessary antibodies that may prevent HIV from attacking the body.

The crucial question, however, is whether the vaccine has any impact on levels of infection in the groups taking the treatment compared to unvaccinated people.

Donald Francis, the head of Vaxgen, said that the vaccine has already been shown to prevent HIV infection in chimpanzees and he was optimistic that it could now also be shown to work on humans.

"I think we will get protection [from the virus], but I don't know what level we'll get. If all goes well, [the vaccine] could be available by the end of 2004 or early 2005," Dr Francis said.

Vaxgen's vaccine is based on a genetically engineered HIV protein, called gp120, which the virus uses to break into a human cell where it takes over the genetic machinery to make copies of itself.

Two earlier clinical trials found that the vaccine was safe and that it appeared to stimulate the immune system to make protective antibodies. However, they failed to establish whether the vaccine has any overall effect on protecting people against HIV infection.